1. Technical Field
The present invention relates to a microlens array substrate, an electro-optical device, and an electronic apparatus.
2. Related Art
An electro-optical device is known which includes an electro-optical material (for example, liquid crystal or the like) positioned between an element substrate and a counter substrate. As the electro-optical device, for example, a liquid crystal device or the like that is used as a liquid crystal light valve of a projector can be used. It is necessary to achieve high light utilization efficiency in the liquid crystal device. Therefore, a configuration is known in which a microlens array substrate is included in the liquid crystal device, the light that is blocked by a light blocking layer, among the light incident on the liquid crystal device, is focused by a microlens, the focused light is incident on an inside of an opening of a pixel, and thereby an actual opening rate of a liquid crystal is increased (for example, refer to JP-A-2004-4745).
The microlens array substrate described in JP-A-2004-4745 is formed by coating a concave portion (dent) of a substrate with a lens layer formed using a high refraction adhesive and by bonding the substrate to a glass plate for adjustment. When the concave portion is formed in the substrate, an undesired material accumulated in the concave portion covers a substrate surface and circulation of an etching solution is inhibited, and thereby the central portion of the concave portion becomes an approximately flat shape. Since a focusing action in the portion of an approximately flat shape is not performed, parallel light that is incident on the central portion of the microlens is not refracted, travels in a straight line as it is, and is emitted from the microlens.
However, the light that is incident on the microlens array substrate includes not only parallel light in the normal direction to the substrate surface, but also considerable amount of inclined light having an angle with respect to the normal direction. In the microlens array substrate described in JP-A-2004-4745, a refractive index of the lens layer is higher than that of a refractive index of the substrate, and a refractive index of the glass plate for adjustment is equal to the refractive index of the substrate. For this reason, the inclined light that is incident on the central portion of the microlens is refracted at an interface between the substrate and the lens layer, and the refraction angle thereof becomes smaller than the incident angle, but the light is refracted again at the interface between the lens layer and the glass plate for adjustment, is returned to an angle at the time of being incident on the microlens and is emitted. For this reason, there is a possibility that the inclined light emitted from the microlens may be blocked by the light blocking portion and thereby utilization efficiency of light may be decreased, or that the light obliquely proceeding with respect to an orientation of liquid crystal molecules is increased and thus a contrast ratio is decreased.